The pressure control system of this invention is connected with a test port at which successive gauges are connected with the system and supplied with pressure of different values to calibrate the accuracy of the gauge.
Pressure is supplied to the system from a source of gas supply such as a bottle or high pressure storage cylinder. A flow control valve or pressure regulator receives the gas from the supply source and delivers it to the system at a controled pressure which depends upon the loading of the regulating chamber of the control valve. This loading depends on adjustable signals supplied to the control valve and such signals are preferably electric signals to solenoids that change the loading on the control valve and the resulting delivery pressure from the control valve.
For pressures in the lower part of the range of the system, the changes can be controlled from the control valve or pressure regulator that receives the gas from the supply source. For higher pressures in excess of those which the control valve can supply, there is a pressure intensifier located between the output of the first control valve and the test port to which gauges are connected.
In the preferred embodiment of the invention, the pressure intensifier includes a pump having a piston which reciprocates to permit entry of gas into the pump from the control valve. The piston then moves in the opposite direction to discharge the gas at a higher and controlled pressure to the test port. In the simplest construction of the invention, the pump piston is connected directly with a piston of a motor of substantially greater displacement than the pump so as to obtain high pump discharge pressure with relatively low pressure supply to the intensifier motor. A displacement ratio of 70 to 1 may be used, by way of example.
A second control valve, referred to as a "mode selector" valve is responsive to pressures at different part of the system and operates to determine when the intensifier becomes necessary in order to maintain desired outlet pressures to the test port.
An auxiliary supply of gas under pressure is controlled by a third control valve which supplies working fluid to the pump for the pressure intensifier and this third control valve is responsive to pressure at other parts of the system in order to make its operation automatic.
The system preferably controls pressure by using a transducer in the test port circuit to generate a feedback signal of low voltage that controls a comparator circuit that regulates the first control valve and indirectly the operation of the pressure intensifier.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.